Ink for etching metal



atented H, 194

INK FOR ETCHING METAL Donald L. Vanda Bunte, Detroit, Mich, assignor to Packard Motor Car Company, Detroit, Mich, a corporation of Michigan No Drawing. Application August 21, 1944,

. Serial No. 550,493

1 Claim.

This invention relates to improvements in etching fluid and more particularly to ink used for etching alloys and metals.

Metal and alloy pieces have been etched with ink solutions to denote various things, such as identity, inspection and quality. Ink is applied to metal or alloy pieces by a rubber stamp or a scriber and forms a reaction product that is bonded to the metal or alloy to provide a. mark of contrasting color. Inks previously employed to etch metals or alloys have provided a reaction product that lacked permanency of bond to metal or alloy pieces and the desired color contrast.

An object of this invention is to provide an ink that will form a reaction product on metals or alloys having a readily discernible contrasting color and a permanent bonded connection.

Another object of this invention is to provide an ink that will react on ferrous metals and alloys to form a permanent marking of contrast ing color.

Another object of the invention is to provide an ink that will react on non-ferrous alloys, such as bronze, brass, aluminum and tin to form a permanent marking of contrasting color.

Still another object of the invention is to provide an ink that will react on ferrous metals to form a permanent bonded marking of a contrasting color.

In carrying out the invention, an ink solution that will satisfactorily mark ferrous metals consists of molybdic acid, hydrochloride acid and nitric acid. The chemical reaction of this solution on ferrous metals will form a product that is much darker than such metals and permanently bonded thereto so that it can withstand handling and other treatments without deterioration. One formula for this solution may be:

Molybdic acid, powder grams Hydrochloric acid, concentrated milliliters 2,450

Nitric acid, concentrated do 530 can be added to the selected solution. When antimony trichloride is added to molybdic acid, hy-

. drochloric acid and nitric acid, the solution will satisfactorily etch ferrous metals and non-ferrous alloys such as copper, brass, bronze and tin, and when added to molybdic acid, hydrochloric acid, nitric acid and copper sulphate, the solution will satisfactorily etch both ferrous metals and non-ferrous alloys such as copper, brass, bronze and tin.

By adding mercuric chloride to the solution of molybdic acid, hydrochloric acid, nitric acid and antimony trichloride, a solution may be provided that will satisfactorily etch aluminum as well as the ferrous metals and non-ferrous alloys previously mentioned. Twenty-three grams of mercuric chloride may be added for this formula. The reaction product from the application of this solution on copper, bronze and brass will have a darker color than when mercuric chloride is eliminated from the solution.

Water may be added to the solutions heretofore described to reduce objectionable fumes, to add bulk and to eliminate any danger of burning persons handling or applying them. As an example, 360 milliliters of water may be added to the above mentioned formulas for the purposes specified. However, it will be understood that water is optional and does not influence the reaction of the solutions on the alloys or metals.

To the ink solutions previously specified, either with or without water, sulphuric acid may be added for the purpose of controlling the time the solutions will remain liquid after application to metal. The timing of the liguid state of the applied solutions regulates the depth to which the chemical reaction takes place below the alloy or metal surface to which the solution is applied, and this obviously may be varied for diiferent uses. As an example. milliliters of sulphuric acid may be added to the previously mentioned formulas to satisfactorily increase the duration of the liquid state of the solution after application to a piece of metal.

It will be understood that the formulas herein set forth are merely examples and that the quantity of the chemicals in the solutions may be varied to some extent.

Molybdic acid in the solutions has the effect of darkening the reaction product so that the color contrast with the alloy or metal to which it is bonded is pronounced. Also the use of molybdic acid in the solutions increases the permanency of the bond of the reaction product with ferrous metals.

It will be understood that variois iorgis of the REFERENCES CITED invention other than those descri ed a on may be used without departing from the spirit or fg; f figgfig fit' m the scope of the invention.

This is a continuation in part of any copend- 5 NITED STATES PATENTS ins application Serial Number 430,073, filed Number February 9. 1942. now Patent Number 2,377,593. 2,080,348 fififf fi issued June 5, 1945.

What is claimed is: An ink for etching metal consisting of molybdic 10 acid, hydrochloric acid. nitric acid and water. DONALD L. VANDE BUNTE.

2,377,593 Vande Bunte June 5. 1945 

